* Makefile.in (DLL_OFILES): Add hookapi.o. Eliminate some cruft.

* cygheap.h (cygheap_types): Add new enum: HEAP_1_HOOK.
(hook_chain): New struct.
(init_cygheap::hooks): Define new element.
* cygheap.cc (cygheap_fixup_in_child): Zero hook chain on exec.
* dcrt0.cc (dll_crt0_1): Call ld_preload just before calling main function.
* external.cc (cygwin_internal): Implement CW_HOOK.
* fork.cc (fork_child): Call fixup_hooks_after_fork.
* init.cc (cygwin_hmodule): Reinstate after a long absence.
* include/sys/cygwin.h: Define CW_HOOK.
* hookapi.cc: New file.
* select.cc (start_thread_socket): Add debugging output.
* fhandler_disk_file.cc (fhandler_disk_file::fchmod): gcc 4.x accommodation.
* fhandler_socket.cc (fhandler_socket::connect): Make sure that err is
initialized.

winsup/cygwin/cygheap.h

@@ -21,6 +21,7 @@ enum cygheap_types
   HEAP_ARCHETYPES,
   HEAP_TLS,
   HEAP_1_START,
+  HEAP_1_HOOK,
   HEAP_1_STR,
   HEAP_1_ARGV,
   HEAP_1_BUF,
@@ -262,6 +263,13 @@ struct user_heap_info
   unsigned chunk;
 };
 
+struct hook_chain
+{
+  void **loc;
+  const void *func;
+  struct hook_chain *next;
+};
+
 struct init_cygheap
 {
   _cmalloc_entry *chain;
@@ -291,6 +299,7 @@ struct init_cygheap
   int open_fhs;
   pid_t pid;			/* my pid */
   HANDLE pid_handle;		/* handle for my pid */
+  hook_chain hooks;
   void close_ctty ();
 };